White is able to pin the knight by 32.Rd1 and can capture this knight on the next move 33.Rxd4+.

3. Attacking a pinned piece

In the diagram on the left White is able to pin the piece, but this piece can be defended by the b-pawn. White is still able to capture this piece, because he is able to attack the piece: 27.Bb4 b6 28.d4 Kg7 29.dxc5